For patients with leukemia who have failed multiple therapies and experienced numerous recurrences, alternative options are limited and extended survival is unlikely.
However, recent research into a new form of immunotherapy for leukemia has shown great promise in battling, and in some cases curing, the disease in these patients with a poor prognosis (< 20% chance of survival).1
Investigators at the Seattle Children’s Hospital opened a phase 1 clinical trial in December 2012, which recruited patients who had relapsed acute lymphoblastic leukemia (ALL) and were not responding to chemotherapy. In this study, patients were given genetically modified T cells—taken from their own blood— that had been reprogrammed to recognize and destroy leukemic cells.
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“The reprogrammed T cells are genetically modified to zero in on the cancer cells and attack only those cells just like they would get rid of a viral infection,” said Michael Jensen, MD, Director of the Ben Towne Center for Childhood Cancer Research at Seattle Children’s Research Institute.
What is, in essence, a genetically modified form of the HIV virus that can seek out and attack only cancer cells, leaves healthy cells untouched—meaning the patient can avoid side effects that often come with traditional chemotherapy and radiation treatment, such as anemia, alopecia, and nausea.1 At this stage, the trial seeks to determine the dose range that is tolerable for patients, as well as any potential toxicities of the treatment.
According to available research, a patient can expect to experience flu-like symptoms over a few weeks upon receiving the modified T cells, which is caused by cytokines produced by the T cells. These symptoms can be readily managed and may serve as a good indication that the cancer is being attacked.2
“It is our hope as we develop and refine this targeted form of immunotherapy we can become less reliant on chemotherapy and radiation therapy that often cause lifelong debilitating side effects,” Dr. Jensen added.
In fact, the first adult patient recruited on the study, a 23-year-old female with ALL, has already responded to the cellular immunotherapy. “Results show that [the patient] has had a positive response to the T-cell therapy and, at this time, we do not detect any leukemia cells,” said Rebecca Gardner, MD, Principal Investigator for the clinical trial. The next step for the patient will be a stem-cell transplant to remove any trace of cancer from her body.3
Last year, a 7-year-old patient with ALL went into complete remission 3 weeks after receiving the same type of T-cell immunotherapy (CTL019 therapy) at the University of Pennsylvania. After 11 months of follow-up, she was still disease-free, and the cancer fighting T cells remained in her body, albeit at lower levels. The pediatric trial in which this patient participated is still ongoing, but initial results released online in March 2013 revealed that CTL019 therapy could, in the near future, be an effective therapy for many patients with B cell cancers, including those with an aggressive, advanced form of the disease. 4
So what is the future for this type of targeted immunotherapy? Initial results seen in a small number of patients treated with T-cell therapy are certainly promising, but more research is needed to evaluate the response of this form of immunotherapy in other hematologic malignancies and in different patient populations. It is also important to continue to assess safety and toxicity levels associated with treatment to ensure that patients’ quality of life is not compromised. Studies are still underway and clinicians at The University of Pennsylvania also plan to test the therapy on other forms of cancer, including mesothelioma, as well as ovarian and pancreatic cancer, which are notoriously difficult to treat.2
It is crucial that healthcare professionals continue to enroll their patients into these clinical trials in order to gather and analyze more detailed data. If the initial results can be duplicated in additional patients and with other cancers, the live-saving potential of this new therapy could be staggering.
References
1. Seattle Children’s Hospital Website. One Step Closer to a Cure for Leukemia without Chemotherapy or Radiation. http://pulse.seattlechildrens.org/one-step-closer-to-a-cure-for-leukemia-without-chemotherapy-or-radiation. Last accessed July 23, 2013.
2. HIV Used to Fight Cancer. http://news.discovery.com/human/health/hiv-used-to-fight-cancer-110914.htm. Last accessed July 23, 2013.
3. Seattle Children’s Hospital Website. Seattle Children’s patient has positive response to new cancer treatment. http://pulse.seattlechildrens.org/seattle-childrens-patient-has-positive-response-to-new-cancer-treatment. Last accessed July 23, 2013
4. Grupp SA, Kalos M, Barrett D, et al. Chimeric Antigen Receptor–Modified T Cells for Acute Lymphoid Leukemia. N Engl J Med 2013; Apr 18;368(16):1509-18.
5. The Children’s Hospital of Philadelphia Website. First Pediatric Patients Treated in T cell therapy Clinical Trial (CTL019, formerly CART19). http://www.chop.edu/service/oncology/pediatric-cancer-research/t-cell-therapy.html. Last accessed July 23, 2013.
